Reduced splattering of unpassivated laser fuses

ABSTRACT

The act of blowing an unpassivated electrical fuse (for example, fuse  405 ) using a laser can result in the splattering of the fuse material and result in electrical short circuits. A blast barrier (for example blast barrier  406 ) formed around an area of the fuse that is blown by the laser helps to contain the splattering of the fuse material. The blast barrier may be formed from the same material as the fuses themselves and therefore, can be created in the same fabrication step.

FIELD OF THE INVENTION

[0001] This invention relates generally to integrated circuitfabrication and particularly to the prevention of the splattering offuse material during the blowing of unpassivated laser fuses fromcreating short circuits in other laser fuses.

BACKGROUND OF THE INVENTION

[0002] Laser fuses have been used for an extended period of time in thefabrication of integrated circuits. One application of laser fuses isthe activation and deactivation of specific functions in an integratedcircuit, depending upon intended use of the integrated circuit. Forexample, a single design for an integrated circuit may be created, witha complete set of functionality. However, depending on the price forwhich the integrated circuit sells, certain functions may be disabled.In another application, the laser fuses permit the replacement of faultydevices and circuits in the integrated circuit with replacement devicesand circuits that are operating properly. Typically, when an integratedcircuit undergoes testing to verify its operation, faulty portions ofthe integrated circuit are marked (or stored) by the test equipment.Subsequently, a separate operation is performed wherein certain laserfuses are blown to eliminate the faulty devices and circuits and toreplace them with devices and circuits that are operational.

[0003] As its name suggests, laser fuses are blown via the use of a highpower laser that effectively melts and then vaporizes the fusable links.During the fusing of the fusable links, it is possible for the vaporizedfuse material to splatter uncontrollably to adjacent fuses. Thesplattered fuse material may then cause adjacent fuses to behaveincorrectly, i.e., cause a previously blown fuse to behave like anunblown fuse or adjacent blown fuses to become short circuited together.If this happens, the integrated circuit does not behave properly.

[0004] Laser fuses come in two major forms, passivated and unpassivated.Passivated laser fuses have a passivation layer formed on top to protectthe laser fuse from damage from its operating environment. The use of apassivation layer is especially important for fusable links made from amaterial that is corrosion-prone, such as copper (Cu). Unpassivatedlaser fuses do not have the passivation layer and are open to damagefrom an unfriendly environment. Since unpassivated laser fuses are opento the environment, they tend to be made from corrosion resistant (orrelatively corrosion resistant) materials, such as aluminum (Al).Passivated laser fuses have very little sensitivity to the splatteringof vaporized fuse material due to the protection afforded by thepassivation layer. On the one hand, the passivation layer makes it moredifficult to blow the laser fuses. This is due to the fact that thelaser used to blow the fuses must have sufficient energy to pass throughthe passivation layer prior to being able to vaporize the fuse materialand to build up sufficient pressure to crack the passivation layer ontop of the fusable link to release the vaporized material.

[0005] On the other hand, the passivation enables the safe blowing ofthe laser fuse without affecting neighboring circuits. This is becausethe passivation layer prevents the immediate and violent release of themolten material of the fusable link. At some point, during the fuseblowing process, after the fusable link is initially melted by thelaser, sufficient energy is absorbed by the fusable link so that theheated fusable link is vaporized. The vaporized material builds up apressure that will tend to crack its encapsulation material at thematerial's weakest point, the weakest point is usually the coveringpassivation layer. The vaporized material explodes from the crack anddeposits itself into a very thin and non-conductive film when itredeposits itself onto the chip surface.

[0006] In integrated circuits that are built up by using materials withlow mechanical stability, e.g. such as low k dielectrics, the crackscreated by the release of the vaporized fuse material may not onlyappear in the pasivation layer, but also in the underlying dielectriclayers. This can cause severe damage to the circuit, in particular, ifcorrosion-sensitive materials such as copper are used for the metalconductive lines. In this case, unpassivated fuses are placed on suchintegrated circuits to reduce the chance that the underlying surfacesare damaged during the fuse blowing process. To provide an additionalmeasure of protection for the underlying surfaces, there can be a harddielectric layer placed between the fuse level and the underlyingsurfaces. Unfortunately, without a passivation layer, the fuse blowingprocess may suffer in the respect that the molten fuse material mayvaporize at a time when there is insufficient heat to prevent the moltenmetal from being vaporized in its entirety. The vaporization of aportion of the molten metal may result in the splattering of the fusematerial that remains in its liquid form. The splattered fuse materialmay cause electrical short circuits in the unpassivated fuses adjacentto the one being blown. The splattering effect is dependent upon manyparameters, such as, the power and wavelength of the laser, thedimensions of the fusable link, the material of the fuse material, etc.

[0007] U.S. Pat. No. 6,160,302 proposes the formation of walls betweenlaser fuses to prevent a misaligned laser from unintentionally blowing afuse that may be adjacent to the fuse that the laser intends to blow.

[0008] U.S. Pat. No. 6,300,232 proposes the construction of barriersaround individual laser fuses to prevent the propagation of physicaldamage resulting from the heat induced by the laser during the fuseblowing step.

[0009] U.S. Pat. No. 5,899,736 proposes fully enclosing the individualelectrically fusable links with a dielectric barrier to prevent theescape of ejected fuse material.

[0010] A need has therefore arisen for a way to provide protection forlaser fuses that are adjacent to a laser fuse that is being blownwithout incurring significant cost increases, in terms of additionalspace requirements and/or additional fabrication steps.

SUMMARY OF THE INVENTION

[0011] In one aspect, the present invention provides a semiconductordevice comprising a first electrical contact pad, a second electricalcontact pad, a fusable link made of a conductive material, the fusablelink having a first end coupled to the first electrical contact pad anda second end coupled to the second electrical contact pad, the fusablelink to become non-conductive after application of an energy source, anda blast barrier horizontally enclosing the fusable link, the blastbarrier to contain fusable link material expelled as a result of theapplication of the energy source.

[0012] In another aspect, the present invention provides a method forcreating a blast barrier for a semiconductor device comprising the stepsof forming a first and a second electrical contact pad, forming afusable link that is coupled to the first and second electrical contactpads, and forming a conductive blast barrier, the blast barrier having afirst piece formed in parallel to the fusable link and a second pieceformed in parallel to the fusable link and on an opposite side of thefusable link from the first piece.

[0013] In yet another aspect, the present invention provides a structurecomprising a first and second pad, a first metal line formed between thefirst and second pads, the first metal line touching the first andsecond pads, and a second and third metal line formed on opposite sidesof the first metal line, the second and third metal lines separated fromthe first metal line by a margin equal to a specified distance.

[0014] In summary, the present invention provides a measure ofprotection against the splattered fuse material of unpassivated laserfuses that may damage the integrity of neighboring fuses. The presentinvention does not require any additional processing steps. Rather, thespecific layout of the metal layer that forms the fusable link ismodified. The present invention provides the protection against thesplattered material through the use of metal lines that run on bothsides of the fusable link. The metal lines may be connected to a viathat establishes an electrical connection to other circuitry, but thelength and other physical characteristics (such as thickness and width)of the metal lines should be set to ensure that electrical connectionbetween the vias connected to the blown fusable link is not possibleafter the fuse blowing process takes place. The metal lines serve as amechanical barrier against splattering molten metal that is generatedduring the fuse blowing process.

[0015] The present invention provides a number of advantages. Forexample, use of a preferred embodiment of the present invention affordsprotection for fuses adjacent to the fuse being blown through the use ofblast barriers that can be fabricated out of the same material as thelaser fuses themselves. By being fabricated out of the same material asthe laser fuses, the blast barriers can be formed during the samefabrication step as the laser fuses, eliminating the need for additionalfabrication steps. This reduces the overall fabrication time and cost ofthe integrated circuit containing the laser fuses when compared to othersolutions that require additional processing steps.

[0016] Also, use of a preferred embodiment of the present inventionpermits the addition of the blast barriers without changing the pitch ofthe laser fuses. Therefore, the density of the integrated circuit is notchanged. The same number of laser fuses can be placed in the same amountof die area.

[0017] Additionally, use of a preferred embodiment of the presentinvention permits the addition of the blast barriers by requiring onlyslightly modifying the fabrication mask used to create the laser fusesthemselves. Therefore, existing designs can be easily modified withoutrequiring any re-routing or replacement of circuits and devices.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above features of the present invention will be more clearlyunderstood from consideration of the following descriptions inconnection with accompanying drawings in which:

[0019]FIGS. 1a, 1 b, and 1 c illustrate top and cross-sectional views ofan unpassivated laser fuse and a top view of a fuse array;

[0020]FIGS. 2a and 2 b illustrate a top view of a fuse array justimmediately prior to and after a laser fuse 205 is blown by a laser;

[0021]FIGS. 3a, 3 b, and 3 cillustrate top and side views of anunpassivated laser fuse with integral blast barrier and a top view of afuse array according to a preferred embodiment of the present invention;

[0022]FIGS. 4a and 4 b illustrate a top view of a fuse array immediatelyprior to and after a laser fuse 405 is blown by a laser, wherein theintegral blast barrier prevents the escape of debris expelled by thevaporization of the fuse material;

[0023]FIG. 5 illustrates an alternate embodiment for a blast barrieraccording to a preferred embodiment of the present invention;

[0024]FIGS. 6a and 6 b illustrate alternate forms of a blast barrieraccording to a preferred embodiment of the present invention; and

[0025]FIGS. 7a-c illustrate alternate embodiments for a fusable linkaccording to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0026] The making and use of the various embodiments are discussed belowin detail. However, it should be appreciated that the present inventionprovides many applicable inventive concepts, which can be embodied in awide variety of specific contexts. The specific embodiments discussedare merely illustrative of specific ways to make and use the invention,and do not limit the scope of the invention.

[0027] Referring now to FIG. 1a, the diagram illustrates a top view ofan unpassivated laser fuse 100 on a hard dielectric layer 115 which lieson top of a substrate 116 (not seen in FIG. 1a, but present in across-sectional view presented later). As discussed previously, anunpassivated laser fuse differs from a passivated laser fuse in that itlacks a passivation layer that protects it from its environment. Whencompared to a passivated laser fuse, an unpassivated laser fuse requiresa less powerful laser to blow its fuse. This is due to the fact that alaser does not have to first pass through the passivation layer beforeit can blow the laser fuse. The use of a higher power laser, in turn,produces a greater amount of heat when the laser energy is absorbed bythe materials that are exposed to the laser. For certain classes ofmaterials, such as special low “k” (a dielectric constant) materials(for example, substrates made from a combination of organic substanceswith silicon), are relatively sensitive to heat and typically cannotwithstand the excessive amount of heat that is typically involved withthe blowing of passivated laser fuses nor the mechanical stresses thatare associated with the blowing of the passivated laser fuses.Additionally, the mechanical properties of materials, such as the low kmaterial, may not be well suited to widthstand the pressure developed bythe rapidly expanding vaporized fuse material.

[0028] The top view of the laser fuse 100 displays the three major partsof the laser fuse: two pads 105 that permit the electrical connection ofthe laser fuse 100 to circuits and devices, and a fusable link 110. Inthe illustrated embodiment, the pads 105 are physically larger than thefusable link 110. In an alternate embodiment, the pads 105 and thefusable link 110 could be the same width (e.g., the fuse would appear tobe a single line). Note that while the fusable link 110 is displayed asbeing a straight line, it is possible that the fusable link 110 beformed in a wide variety of shapes, such as a zig zagged line, a curve,a line of varying width and thickness, etc. The pads 105 are the portionof the line that permit the attachment of electrically conductive linesto the semiconductor device.

[0029] The fusable link 110 is the part of the laser fuse that is heatedby the laser and is subsequently broken. Preferably, the two pads 105and the fusable link 110 are made of the same electrically conductivematerial. The fusable link 110 may be fabricated from practically anytype of metal, but aluminum is a preferred material, due to itsrelatively low melting point and relatively non-reactive properties.Additionally, aluminum is well established as the metal of choice forsemiconductor fabrication. Other materials that can be used for thefusable link 110 include gold, and less preferably, copper and silver.Various alloys are also usable, as long as they are relatively immune tocorrosion.

[0030] Referring now to FIG. 1b, the diagram illustrates across-sectional view of the laser fuse 100 on the hard dielectric layer115 on top of the substrate 116 displayed in FIG. 1a, with thecross-section made along a dotted line labeled B-B. The cross-sectionalview displays the two pads 105 having conductive channels going throughthe hard dielectric layer 115 and down into the substrate 116 that areconnected to connection points 120 for electrical circuits and devices.

[0031] Referring now to FIG. 1c, the diagram illustrates a fuse array150 of three laser fuses arranged in linear fashion. It is typical toarrange laser fuses in an array, configured as closely together aspossible to minimize the amount of surface area that they consume in theintegrated circuit. The separation between the fuses is referred to asthe fuse pitch, which is defined as the width of the fuse plus thespacing between two adjacent fuses; the smaller the fuse pitch, thecloser the fuses are together. The fuse array 150 illustrated in FIG. 1chas three laser fuses (155, 160, and 165), but it is possible for fusearrays to have any number of fuses grouped together, with a constrainton the number of fuses in a fuse array being the physical size of thesemiconductor surface area.

[0032] Fuses may be blown in a variety of ways, for example, electricalcurrent is another way to blow fuses. However, due to the delicatenature of most devices and circuits in an integrated circuit, fusesusing electrical current to blow the fusable links are not commonlyused. Fuses may also be blown by exposing them to radioactive energy. Inany event, the present invention also applies to fuses that are blown inways other than by use of a laser.

[0033] Laser fuses use a laser to heat-up and vaporize their fusablelinks. The use of a laser to melt and then subsequently sever thefusable link is the same, regardless if the laser fuses are of thepassivated or unpassivated variety. With passivated laser fuses, thelaser must pass through the passivation layer before it can vaporize thefusable link. This may be achieved by using a laser of a particularwavelength that is not absorbed by the passivation layer. For example, acommonly used passivation layer, SiO₂, permits laser energy of a certainwavelength to pass without absorbing a significant amount of the laser'senergy. The laser's energy can then be focused on blowing the fusablelink.

[0034] Referring now to FIG. 2a, the diagram illustrates a fuse array200 wherein a laser spot 220 has been placed onto a fusable link of alaser fuse 205 for the purpose of blowing the laser fuse. It is possibleto blow a laser fuse by placing the laser spot 220 relatively close toone end of the fusable link. This can facilitate the ability to blow thelaser fuse's fusable link at two locations, one near each end of thefusable link.

[0035] As discussed previously, the fusable link is blown by the heatingaction of the laser spot 220. First the fuse material of the fusablelink is melted and then vaporized. The melting and vaporizationoperation is extremely short in duration to prevent the excessivebuild-up of heat; basically, the fusing process is finished before theheat is dissipated to areas outside the fuse link area. Therefore, themelting and vaporization of the fuse material can often take on theresemblance of an explosion, wherein the fuse material targeted by thelaser spot 220 effectively explodes.

[0036] As discussed previously, if the laser fuses were of thepassivated laser fuse variety, then the debris from the explosion wouldmost likely not cause any problems for two possible reasons: a firstreason being that the passivation layer provides a significant level ofprotection since it covers the surface of the adjacent fuses, and asecond reason being that the passivation layer holds the molten fusematerial captive until it has become fully vaporized and the debrisgenerated by the vaporized fuse material tends to be non-conductive dueto being dispersed over a large area. However, with unpassivated laserfuses, the molten fuse material is not contained and may be ejectedwhile in a molten state. If the fuse material is ejected in a moltenstate, it may not disperse enough to become non-conductive. Therefore,the debris may result in short circuits. Depending on where the debrislands, laser fuses adjacent to the one being blown may be shortcircuited to itself (a problem if the adjacent fuse(s) has previouslybeen blown) or adjacent laser fuses may be electrically short circuitedto each other.

[0037] Referring now to FIG. 2b, the diagram illustrates a fuse array250 wherein a first laser fuse 205 has been blown by a laser and debris(for example, pieces of fuse material 255) from the operation haselectrically short circuited adjacent laser fuse 210 to the first laserfuse 205. As an example, the pieces of fuse material 255 that wasejected from the molten fuse material of the fusable link of the firstlaser fuse 205 has formed an electrical bridge between the first laserfuse 205 and the adjacent laser fuse 210, shorting the two laser fusestogether. Since each of the laser fuses are connected to differentelectrical circuits, an integrated circuit containing laser fuses areshorted together would most likely not operate properly and would likelybe discarded.

[0038] Referring now to FIG. 3a, the diagram illustrates a top view of alaser fuse 300 on a hard dielectric layer 320 on top of a substrate 321(not seen in FIG. 3a, but present in a side view presented later)wherein the laser fuse 300 has built-in blast barriers 315 that help toprevent the ejection of molten fuse material from creating electricalbridges with adjacent laser fuses according to a preferred embodiment ofthe present invention. The blast shields are formed on each side of afusable link 310 and on each end of the fusable link 310, forming ahorizontal enclosure around an area of the fusable link 310 where thelaser will burn through the fusable link 310. Note that as discussedpreviously, the fusable link 310 although displayed as a straight line,it may take other forms, such as a zig zagged line, a curve, a line ofvarying widths, etc. According to a preferred embodiment of the presentinvention, the blast barriers 315 are formed from the same material asthe laser fuse itself. Therefore, the blast barriers 315 can be createdin the same fabrication step as the laser fuse, saving additionalfabrication steps. However, it is possible to form the blast shields 315from any other type of material that is compatible with the fabricationof the integrated circuit, including from non-conductive materials.

[0039] Since, according to a preferred embodiment of the presentinvention, the blast barriers 315 are created from the same material asthe laser fuse or from any electrical conducting material, it isnecessary that the blast barriers 315 on each end of a single laser fusenot come into contact with each other. If they do come into contact witheach other, the net effect is the creation of an electrical conductivelink in parallel to the fusable link. If the blast barriers 315 arecreated from a non-electrically conductive material, then the blastbarriers 315 of a single laser fuse can be permitted to come intocontact with one another. Also, due to vias, channels, and otherfeatures that may be formed in the substrate beneath the laser fuses, itmay not be possible to form a blast barrier that runs the entire lengthof the fusable link.

[0040] Referring now to FIGS. 3b and 3 c, the diagrams illustrate a sideview (with a point of view set at approximately 45 degrees above thehorizon) of the laser fuse 300 with blast barriers 315 and a top view ofa fuse array 350 with three laser fuses 355, 360, and 365. Sinceaccording to a preferred embodiment of the present invention, the blastbarriers are formed in the same fabrication step as the formation of thelaser fuses, the height of the blast barriers will be approximatelyequal to the height of the laser fuse itself. However, if the blastbarrier was to be formed using a different fabrication step, the heightof the blast barrier may be set to a height that would maximize itseffectiveness. This may mean that the blast barrier be created to aheight as high as the laser fuses or that they may be made higher thanthe laser fuses. Note that due to the design of the blast barriers, thefuse pitch of the array 350 has not been changed (compared with the fusearray 150 displayed in FIG. 1c). Therefore, it is possible to place asimilar number of laser fuses made in accordance with the presentinvention as the unprotected laser fuses.

[0041] Referring now to FIG. 4a, the diagram illustrates a fuse array400 made up of laser fuses with blast barriers and where a laser dot 420has been placed on a fusable link of a laser fuse 405 for the purpose ofbreaking the fusable link according to a preferred embodiment of thepresent invention. Immediately surrounding the fusable link of the laserfuse 405 are blast barriers 406. Note that in order for the blastbarriers to be fully effective, the blast barriers 406 should extendpast the region of the fusable link that will be vaporized by the laserdot 420. If the blast barrier 406 does not extend past the region of thefusable link that is to be vaporized, then the effectiveness of theblast barrier may be compromised, and vaporized fuse material that isnot blocked by the blast barrier may be able to create electrical shortcircuits with other laser fuses.

[0042] Referring now to FIG. 4b, the diagram illustrates a fuse array450 wherein a first laser fuse 405 has been blown by a laser and debris(for example, pieces of fuse material 455) from the operation has beenblocked by blast barriers 406 surrounding the first laser fuse 405according to a preferred embodiment of the present invention. The debris455 that was formed by the vaporization of the fuse material by thelaser, for example, the laser dot 420 (FIG. 4a), which would havenormally splattered in an unpredictable fashion and over anunpredictable distance, is contained within the blast barriers 406formed in the vicinity of the place where the first laser fuse 405 is tobe blown. The blast barriers 406 create an enclosure around the blastarea and contain vaporized fuse material that is ejected during the fuseblowing process.

[0043] According to a preferred embodiment of the present invention, theblast barriers may be formed in the same fabrication step as the laserfuses and are created from the same material as the fuses.Alternatively, the blast barriers are created out of any material thatis compatible with the fabrication process used to create the integratedcircuit. If an additional fabrication step is to be used to create theblast barriers, it is preferred that the blast fuses be created out ofan electrically non-conductive material.

[0044] Referring now to FIG. 5, the diagram illustrates a laser fuse 500with blast barriers 515 shaped in the form of an L according to apreferred embodiment of the present invention. The blast barriers 515are created in the form of an L, with the long portion of the L runningfrom the pad and the short perpendicular portion creating a morecomplete enclosure for the portion of a fusable link 510 to be blown.Note that if the blast barrier 515 is formed from an electricallyconductive material, such as the fuse material itself, it should not bepermitted to touch the fusable link 510 except at one end (such asthrough a pad 505). Alternatively, the blast barriers can be formed inother shapes that are as equally as effective in fully enclosing theportion of the fusable link to be blown.

[0045] Referring now to FIGS. 6a and 6 b, the diagrams illustratealternate embodiments for laser fuses with blast barriers according to apreferred embodiment of the present invention. In FIG. 6a, the diagramillustrates a laser fuse 600 with a blast barrier 615 that is notcoupled electrically to either a pad 605 or a fusable link 610 and theblast barrier 615 is electrically decoupled from itself (i.e., theportion of the blast barrier around one end of the laser fuse 600 is notcoupled to the portion of the blast barrier around the other end). Whilein FIG. 6b, the diagram illustrates a laser fuse 650 with a blastbarrier 665 that is not coupled electrically to either pad 655 or afusable link 660, but the blast barrier 665 formed from a single unitthat protects the entire length of the fusable link 660.

[0046] Referring now to FIGS. 7a-c, the diagrams illustrate alternateembodiments for a fusable link according to a preferred embodiment ofthe present invention. In FIG. 7a, the diagram illustrates a fusablelink 710 in the form of a zig zagged line, while in FIG. 7b, a fusablelink 720 in the form of a curved line is presented. Finally, in FIG. 7c,a fusable link 730 in the form of a line with varying line width isillustrated. Other embodiments for the structure of the fusable link ispossible, with the final form being dictated by constraints such as adesired resistivity, a maximum amount of current carried, a topographyof the underlying substrate, etc.

[0047] According to another preferred embodiment of the presentinvention, the height of the blast barriers is equal to the height ofthe laser fuse. However, the height of the blast barrier can be variedso that its height may be greater than or less than the height of thelaser fuse in order to more effectively enclose the vaporized blastmaterial.

[0048] While this invention has been described with reference toillustrative embodiments, this description is not intended to beconstrued in a limiting sense. Various modifications and combinations ofthe illustrative embodiments, as well as other embodiments of theinvention, will be apparent to persons skilled in the art upon referenceto the description. It is therefore intended that the appended claimsencompass any such modifications or embodiments.

What is claimed is:
 1. A semiconductor device comprising: a firstelectrical contact pad; a second electrical contact pad; a fusable linkmade of a conductive material, the fusable link having a first endcoupled to the first electrical contact pad and a second end coupled tothe second electrical contact pad, the fusable link to becomenon-conductive after application of an energy source; and a blastbarrier horizontally enclosing the fusable link, the blast barrier tocontain fusable link material expelled as a result of the application ofthe energy source.
 2. The semiconductor device of claim 1, wherein theblast barrier, the fusable link, and the first and second electricalcontact pads are made from a same material, and are fabricated during asame fabrication step.
 3. The semiconductor device of claim 2, whereinthe blast barrier is electrically decoupled from the first and secondelectrical contact pads.
 4. The semiconductor device of claim 2, whereinthe blast barrier is electrically decoupled from the fusable link. 5.The semiconductor device of claim 2, wherein the blast barrier is formedto a higher physical height than the fusable link and the first andsecond electrical contact pads.
 6. The semiconductor device of claim 1,wherein the blast barrier comprises two pieces, wherein a first piecelocated adjacent to one side of the fusable link and oriented parallelto the fusable link and wherein a second piece of the blast barrierlocated adjacent to an opposite side of the fusable link from the firstpiece and oriented parallel to the fusable link.
 7. The semiconductordevice of claim 6, wherein the two pieces of the blast barrier areshaped like linear segments.
 8. The semiconductor device of claim 6,wherein there are two blast barriers, and wherein a first blast barrieris coupled to the first electrical contact pad and a second blastbarrier is coupled to the second electrical contact pad, and wherein thefirst and second blast barriers are electrically decoupled.
 9. Thesemiconductor of claim 6, wherein the fusable link is exposed to a laserto cause a break in the fusable link, and the blast barrier horizontallyencloses the fusable link at a location where the fusable link isexposed to the laser.
 10. The semiconductor device of claim 1, whereinthe fusable link is made of a low resistance electrically conductivematerial with a low melting point.
 11. The semiconductor device of claim1, wherein the energy source is a laser.
 12. The semiconductor device ofclaim 1, wherein the energy source is a current supply.
 13. Thesemiconductor device of claim 1, wherein the blast barrier is made ofthe same material as the fusable link.
 14. A method for creating a blastbarrier for a semiconductor device comprising: forming a first and asecond electrical contact pad; forming a fusable link that is coupled tothe first and second electrical contact pads; and forming a conductiveblast barrier, the blast barrier having a first piece formed in parallelto the fusable link and a second piece formed in parallel to the fusablelink and on an opposite side of the fusable link from the first piece.15. The method of claim 14, wherein the two pieces of the blast barrierare electrically decoupled from the first and second electrical contactpads and the fusable link.
 16. The method of claim 14, wherein the threeforming steps are performed in a same fabrication step.
 17. The methodof claim 14, wherein the conductive blast barrier is formed at a firstend of the semiconductor device, and the method further comprising thestep of forming a second conductive blast barrier, wherein the secondblast barrier is formed at a second end of the semiconductor device, andwherein the second blast barrier having a first and second piece, thefirst piece of the second blast barrier formed in parallel to thefusable link and the second piece of the second blast barrier formed inparallel to the fusable link and on an opposite side of the fusable linkfrom the first piece of the second blast barrier.
 18. The method ofclaim 17, wherein the first and second pieces of the blast barrier areelectrically decoupled from the first and second pieces of the secondblast barrier.
 19. The method of claim 17, wherein the four formingsteps are performed in a same fabrication step.
 20. A structurecomprising: a first and second pad; a first metal line formed betweenthe first and second pads, the first metal line touching the first andsecond pads; and a second and third metal line formed on opposite sidesof the first metal line, the second and third metal lines separated fromthe first metal line by a margin equal to a specified distance.
 21. Thestructure of claim 20 further comprising: a fourth and fifth metal lineformed on an opposite end of the first metal line from the second andthird metal lines, the fourth and fifth metal lines separated from thefirst metal line by a margin equal to the specified distance.
 22. Thestructure of claim 21, wherein the second and third metal lines touchthe first pad and the fourth and fifth metal lines touch the second pad.23. The structure claim of 22, wherein the second and third metal linesdo not touch the fourth and fifth metal lines.
 24. The structure ofclaim 20, wherein the first metal line is in the form of a zig zaggedline.
 25. The structure of claim 20, wherein the first metal line is inthe form of a curved line.
 26. The structure of claim 20, wherein thefirst metal line is in the form of a line with varying width.